In intensive medicine the determination of blood values, for example of the total protein or the electrolyte, is of particular signigicance. If for example during an intensive treatment an infusion therapy by means of potassium is carried out a practically continuous monitoring of the blood potassium values is necassary because an ovedose or inadequate dose can have serious consequences.
In such a therapy for monitoring the blood values usually the blood necessary for the investigation is take from the patient via a separate additional blood connection, for example a catheter. A disadvantage is then however that the patient is additionally subjected to the strain of this further blood removal catheter.
German Pat. No. 3,313,074 discloses an apparatus with which blood and other body fluids can be taken from a patient and supplied to a sample taking device. After withdrawal of coagulable body fluids the device is intermittently flushed with a flushing solution, whereupon the withdrawal operation starts again. The known apparatus is however not used for infusion of a fluid and is rather a block sampling means which is used in addition to an infusion apparatus and this leads to the disadvantages mentioned above.
German specification as laid open to inspection No. 2,644,062 and German Pat. No. 3,235,744 disclose single-needle hemodialysis apparatuses in which blood is led in an extracorporeal cycle through a dialyzer and freed there from metabolism products. Such a hemodialysis machine is however neither an infusion apparatus nor a sample taking apparatus but rather a blood cleaning machine which serves for purification and not for infusion or taking samples.